Valorization of mustard and sesame oilseed cakes for food application through eco‐innovative technologies

Abstract Agricultural waste valorization is currently getting attention across the world owing to its environmental impact and rich phytochemistry. The mandate of the current investigation was the extraction and characterization of bioactive moieties from the mustard oilseed cake/meal MOC and sesame oilseed cake/meal SOC through ultrasound extraction (UE) techniques due to its higher yield and less burden on the environment as compared to conventional extraction (CE). Purposely, the MOC and SOC were initially subjected to compositional analysis. Thereafter, bioactive moieties were extracted by using different solvents, that is, ethanol and distilled water, and by applying conventional and ultrasonic extraction techniques. The outcomes indicated that among the techniques, ultrasound exhibited the highest results, and in solvents, ethanol performed better. The treatment extracted with ethanol with UE at 10 min showed the best result for total phenolic contents (TPC) as (6.07 ± 0.03 09 g GAE/100 g MOC) and (7.09 ± 0.04 g GAE/100 g SOC), DPPH radical scavenging activity (67.3 ± 1.9 TE/100 g MOC) & (72.68 ± 1.9 TE/100 g SOC), and FRAP was recorded as (2.83 ± 0.02 g TE/100 g MOC) & (3.56 ± 0.03 g TE/100 g SOC). The higher antioxidant potential showed that the mustard and sesame waste holds significant therapeutic potential owing to its rich antioxidant profile and thus should be utilized for the development of functional products against lifestyle‐related disorders. In conclusion, ultrasound is a better technique for maximum as well as accurate extraction, with ethanol exhibiting as a better solvent for this process with more yields as compared to distilled water.


| INTRODUC TI ON
Food security is defined as reliable social, economic, and physical access to safe and sufficient amounts of food. It is estimated that in 2020, about 12% of the total population was food insecure accounting for almost 928 million people. In Pakistan, the situation is also very alarming, as 60% of the total population's food is secure.
The food waste or byproducts may be from agriculture production, inappropriate postharvest handling or storage, and negligible processing or packaging during distribution or consumption. The ever-increasing volume of byproducts or waste from agro-based industries has turned out to be a major trouble for industrialists (Sadh et al., 2018). Mostly, the agro waste or byproducts are untreated, unutilized, and disposed of in inappropriate methods like burning, land, filling, dumping, etc., which result in harmful environmental impact (Cecilia et al., 2019). The utilization of agricultural waste or byproducts requires less waste disposal, which is more profitable, and more economical. Commonly, agro-industrial wastes include two types, that is, waste from agriculture and waste from industry. Waste from agriculture includes field waste and process waste. Field wastes or residues include seeds, pots, stems, leaves, and stalks, while the process residues are obtained as a result of crop processing including peel, roots, tubers, stubble, etc., which can be utilized for animal feed. The productions in food industries such as beverages, confectionary, bakeries, and oil generate a large volume of food waste or byproducts that accounts for food industrial waste. Oilseeds are generally known as the most common source of ingredients used in functional foods. Oilseeds are loaded with fiber, fats, vitamins, proteins, carbohydrates, phytochemicals (such as phenolic compounds, tocopherols, flavonoids, tocotrienols, and lignans) and a few antinutritional factors (e.g., phytates glucosinolates) (Ramachandran et al., 2007). Oilseeds, because of their antioxidant potential, help to combat different diseases, especially different types of cancer (Abiodun, 2017). Oil meals or oil cakes are byproducts that remain after the extraction of oil from oil seeds. There are two types of oil cakes: edible oil cakes and non-edible oil cakes. The nutritional value of edible oil cakes is higher than that of non-edible oil cakes. The protein content of edible oil cakes varies from 15% to 50% (www. seaoW ndia.com). Fruits, vegetables, and cereals are among the top food groups which generate maximum waste or byproducts followed by other groups such as dairy, meat, and eggs. On average, globally, approx. 65 kg per year of food is wasted by each person (25% wasted vegetables, 24% wasted cereals, and 12% wasted fruits) (Chen et al., 2020). Brassicaceae oilseed crops such as Brassica juncea (mustard) are important due to their ability to support the ever-growing biofuel industry. The extracts of mustard (Brassicaceae seed metals) have tremendous antioxidant activity resulting from the phenolic compounds present in them (Shahidi et al., 1994). Sesame indicum belongs to the Pedaliaceae family. Sesame seeds are vital oilseed crops.
Sesame seeds have various phenolic compounds such as ferulic, cinnamic coumaric, and vanillic acids. Mohdaly et al. (2013Mohdaly et al. ( , 2013 report showed significant biological properties. It was confirmed by various in vitro studies that phenolics and lignans existing in sesame seeds showed excellent antioxidant properties (Suja et al., 2004;Kumar & Singh, 2015;Sarkis et al. 2014). Extraction is the method that is used to obtain extracts. By employing different techniques like soxhlet, microwave-assisted extraction, orbital shaker, supercritical fluid extraction, and ultrasound-assisted extraction, antioxidants have been isolated from different plants (Sultana et al., 2009). For the selection of the optimal technique for antioxidant extraction, the choice of solvent is the most critical. Mostly organic solvents are used for this purpose (Kaneria et al., 2012). Conventional extraction techniques include maceration, digestion, infusion and Soxhlet extraction, etc.
Extraction by these methods has been done for many years. Soxhlet and maceration are the most commonly used techniques. Ultrasound technique, by increasing mass transfer and bursting cellular matrix, releases a maximum amount of targeted compounds. In this method, as a result of exposure to ultrasound, acoustic cavitation activity results in microbubbles formation and grows in the liquid phase. Due to pressure changes, it oscillates swiftly. In case of plant material, ultasound extraction (UE) waves modify the cavitation effect as well as physiochemical properties to stimulate the extractable compounds' release and enhance mass transport by cell wall disruption.
The aim of current investigation was to evaluate extraction efficiencies of oilseed cakes (mustard and sesame) from conventional and ultrasonic techniques using distilled water and ethanol as solvents.

| Procurement of raw material
Oilseed meal/cake generated from mustard and sesame seeds during processing was collected from the local market of Faisalabad.
The oilseed cakes were cleaned to remove dirt, dust, and foreign materials, and were put in polythene bags and then stored in a refrigerator until used. After that, the extract was prepared by using solvents, distilled water, and 70% ethanol.

| Proximate analysis
Proximate composition of mustard and sesame oilseed cake/meals was calculated through the determination of moisture, fat, protein, fiber, and ash by following the guidelines of Kaur et al. (2014), whereas nitrogen free extract (NFE) was calculated using the subtraction method (AACC, 2000).

| Mineral analysis
In mineral analysis, the mustard and sesame oilseed cake/meal samples were determined for minerals like sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), copper (Cu), and phosphorus (P) by the standard protocol of Costa et al., (2002). The first two minerals were estimated by using a Flame Photometer-410 (Sherwood Scientific Ltd., Cambridge), while the remaining were estimated by using an atomic absorption spectrophotometer (Varian AA240, Australia).

| Preparation of antioxidant extract
The extraction of phenolics from mustard and sesame oilseed meal was carried out through the Soxhlet extraction method. For the preparation of extracts, that is, ethanol, distilled water solvents were used. Samples were placed in the respective apparatus at room temperature for 7 h. From every flask, the supernatant was filtered using a muslin cloth. From the supernatant, the solvent was separated in a rotary vacuum at 50°C and the crude extract was left behind. (Eyela, N-N series, Japan). Each sample extract was weighed to evaluate the antioxidant extract yield and storage was done at 4°C.

| Analysis of antioxidant extract
The extract of antioxidants gained from mustard and sesame oilseed cake was evaluated for their antioxidant potential by various parameters such as TPC (total phenolic contents), DPPH (1,1-diphenyl-2-picrylhydrazyl) assay, and FRAP (ferric-reducing antioxidant power) assay (Table 1). Table 1.

| Conventional extraction
Extraction from mustard and sesame oilseed cake was done separately following Rodriguez-Saona and Wrolstad (2001) with slight modifications. Five grams of sample (mustard and sesame oilseed cake) was added in 100 ml of water and ethanol solvent at an interval of 30, 60, and 90 min at 60°C temperature. By using a muslin cloth, these extracts were filtered. Then, these extracts were stored in air-tight bottles. These extracts were kept at refrigeration temperature to prevent fungal attack. These extracts were stored in air-tight bottles.

| Ultrasound-assisted extraction
The ultrasonic extraction of bioactive moieties was estimated by following the procedures of Rusak et al. (2008) with slight modifications. As extraction solvents, ethanol and distilled water were utilized. Three different parameters were as follows: Temperature (30°C, 40°C, and 50°C), time (30, 60, and 90 min CE) (5, 10, and 15 min US), sample to the solvent ratio (10:50), and amplitude (20%, 30%, and 40%). were then concentrated and finally changed into a powdered form by utilizing freeze-drying. These were then stored at the optimum required conditions. The following processing conditions of time and temperature were chosen based on the former results of the polyphenol extraction by utilizing these modules followed by the same research group. In addition to this, in the preliminary experiments, these conditions revealed better consequences among the various tested processing combinations.

| Phytochemical screening assays
The antioxidant assays were carried out through the TPC, DPPH, and FRAP assay estimation.

| Total phenolic contents (TPC)
Total phenolic contents were the most important assay to estimate the antioxidant potential of the tested MOC and SOC samples. For this purpose, an equal amount of FC reagent and the sample (MOC,

Ferric-reducing antioxidant power (FRAP)
The metal ion chelation ability is another parameter to assess the antioxidant capacity of the tested compounds under different challenges and for this, ferric-reducing antioxidant power is the most adopted test. For the estimation of FRAP, 0.5 ml of sample was added in 125 ml of phosphate buffer prepared 0.2 M and pH of 6.6 and potassium ferricyanide solution (1%) and placed in the water bath at 50°C for 15 min. In the resulting sample, an equal amount of 1.25 ml trichloroacetic acid (10%) and distilled water alongside 0.25 ml of ferric chloride (1%) was added kept for 10 min and the reading was recorded at 700 nm.

| Statistical analysis
To check the level of significance, data for all parameters were statistically analyzed. One-way and two-way ANOVA were performed for analysis of variance and estimation of the significance among mean values. Tukey's HSD test was applied. The calculated values are represented as mean ± SD.

| Extraction and assessment of bioactive moieties
The mean square regarding the antioxidant indices of mustard and sesame oilseed meal illustrates the significant impact of each technique, solvent, and time interval on the traits.
However, their interactions showed a non-significant trend.

| Result & discussion
The means showed the highest polyphenols yield in ultrasound fol- the highest ratio achieved in time for ultrasonic and less for conventional was 10 and 60 min followed by 15 and 90 min and minimum for 5 and 30 min, respectively (Table 3). Means exposed the highest MOC polyphenols extraction rate from ultrasonic while the lowest for the conventional technique was 5.64 ± 0.12 g GAE/100 g of mustard oilseed cake and 5.33 ± 0.13 g GAE/100 g of MOC, respectively. Among the solvents, ethanol caused a more potent effect as 5.79 ± 0.13 and 5.47 ± 0.15 g GAE/100 g of MOC followed by distilled water 5.50 ± 0.10 and 5.19 ± 0.12 g GAE/100 g of MOC in ultrasound and conventional extraction, respectively (Table 3).
Our results showed that MOC has an appreciable amount of polyphenols. According to Ahmed et al. (2011), poly-phenols yield is affected by various factors like extraction techniques and medium. Albu et al. (2004) reported that TPC extraction from MOC can be collected at a higher concentration by using ultrasound technology.
Means exposed the highest sesame oilseed cake/SOC polyphenols extraction rate from ultrasonic, while the lowest for the conventional technique was 6.60 ± 0.01 g GAE/100 g of sesame cake and 6.29 ± 0.03 g GAE/100 g of SOC, respectively. Among the solvent, ethanol caused a more potent effect as 6.77 ± 0.03 and 6.45 ± 0.03 g GAE/100 g of SOC followed by distilled water 6.43 ± 0.02 and 6.13 ± 0.02 g GAE/100 g of SOC in ultrasound and conventional extraction, respectively ( Table 3) Rubalya et al. (2015) also studied DPPH scavenging activity of mustard.
Means regarding DPPH-free radical scavenging activity also showed the same trend with high 69.37 ± 3.5 g TE/100 g SOC in U.E and C.E 67.2 ± 0.5 TE/100 g SOC for aqueous ethanol followed by water with 65.92 ± 0.7 and 63.8 ± 0.6 g TE/100 g SOC, respectively.

ACK N OWLED G M ENTS
The authors are thankful to the Government College University, Faisalabad. Moreover, the authors are highly thankful to the higher education commission of Pakistan.

FU N D I N G I N FO R M ATI O N
No funding was received for this study.

CO N FLI C T O F I NTE R E S T
The authors declare no conflict of interest.

DATA AVA I L A B I L I T Y S TAT E M E N T
Even though adequate data have been given, all authors declare that if more data are required, then the data will be provided on a request basis.

E TH I C A L A PPROVA L
This article does not involve humans or animals.

CO N S E NT TO PA RTI CI PATE
All the co-authors are willing to participate in this study.

CO N S E NT FO R PU B LI C ATI O N
All authors are willing for the publication of this manuscript.